Odometer for a vehicle

Abstract

An odometer i.e. a distance recorder, for a vehicle has a counting mechanism driven by a stepping mechanism which is in turn driven with rotation of a vehicle wheel. The stepping mechanism has a plurality of pawls which reciprocate with wheel rotation and which can advance respective ratchet wheels. For a given vehicle wheel size, one of the pawls is selected to operate its ratchet wheel by a cam means which then disables the or each other pawl from engagement with associated ratchet(s).

We claim: 
     
       1. An odometer comprising a stepping mechanism to be driven with rotation of a wheel of a vehicle, and a counting mechanism connected to be driven by the stepping mechanism, said stepping mechanism comprising: at least two ratchet wheels mounted on a shaft; said ratchet wheels being of different sizes and corresponding to different vehicle wheel sizes; respective pawls cooperating with said ratchet wheels; means to reciprocate said pawls upon rotation of the vehicle wheel so as to rotate said ratchet wheels; and a device for selectively disabling all except a selected one of said pawls from rotating the associated ratchet wheels, said one pawl being selected according to vehcile wheel size. 
     
     
       2. A odometer as claimed in claim 1 and comprising a single common shaft on which each said ratchet wheel is securely mounted. 
     
     
       3. An odometer as claimed in claim 2 and further comprising a transmission element coupled to said common shaft, said transmission element drivingly engaging said counting mechanism. 
     
     
       4. An odometer as claimed in claim 1, wherein said disabling device comprises a cam means having a cam surface for each said pawl, said surfaces being so arranged that when one pawl interacts with the associated ratchet wheels each other pawl is displaced to a position of non-interaction with the associated ratchet wheels. 
     
     
       5. An odometer as claimed in claim 1 and further comprising a friction brake associated with said ratchet wheels to hinder reverse rotation thereof. 
     
     
       6. An odometer as claimed in claim 1 and further comprising an additional pawl engageable with each said ratchet wheel to prevent reverse rotation of said ratchet wheels.